- #1
MaJiK9021
- 4
- 0
Hi,
I've been doing some research on an idea of mine, part of which involves levitating a sphere. Apparently Earnshaw's theorem makes this very difficult; but I'm having a hard time imagining why. I'm imagining the sphere as a magnet, with the north pole over the entire outer surface of the sphere and the south pole over the entire inner surface of the sphere. Two magnetic rings circle around the sphere, each parallel to the equator, but one above and one below the equator. These magnetic rings come close to contact with the sphere, but not quite. The rings are oriented so that their north pole is facing the sphere, causing a repulsive force between the rings and the sphere. The rings are held in place by a bar (or whatever) that is attached to both rings and the ground, keeping the rings firmly in place.
With this setup, would the sphere not stably remain levitated within the rings? I'm trying to understand how Earnshaw's theorem would allow this setup to be unstable. Whichever way the sphere moves, it will move towards a repulsive magnet, which will cause it to move back to an equilibrium right in the middle of the rings. Right?
I've been doing some research on an idea of mine, part of which involves levitating a sphere. Apparently Earnshaw's theorem makes this very difficult; but I'm having a hard time imagining why. I'm imagining the sphere as a magnet, with the north pole over the entire outer surface of the sphere and the south pole over the entire inner surface of the sphere. Two magnetic rings circle around the sphere, each parallel to the equator, but one above and one below the equator. These magnetic rings come close to contact with the sphere, but not quite. The rings are oriented so that their north pole is facing the sphere, causing a repulsive force between the rings and the sphere. The rings are held in place by a bar (or whatever) that is attached to both rings and the ground, keeping the rings firmly in place.
With this setup, would the sphere not stably remain levitated within the rings? I'm trying to understand how Earnshaw's theorem would allow this setup to be unstable. Whichever way the sphere moves, it will move towards a repulsive magnet, which will cause it to move back to an equilibrium right in the middle of the rings. Right?